The spectral properties of the homogeneous immunoglobulin products (Bence Jones proteins, myeloma proteins, and Waldenstrom macroglobulins) of human cell neoplasms will be determined. The data obtained through luminescence (fluorescence and phosphorescence), polarization, and circular dichroic studies on these immunoproteins and their subunits will contribute to the basic knowledge on the tertiary structure of immunoglobulins. The spectroscopic data will be correlated with available sequence, immunochemical, and molecular structural data. The extension of these studies to molecules of known antibody specificity (cold agglutinins, rheumatoid factors, etc.) will be important in the elucidation of the nature of antibody structure as it relates to antibody function. The structural approach to the study of immunoglobulins has been instrumental in providing the current knowledge on antibody structure. Moreover, the application of this approach to other areas of immunology not only is feasible but also is important especially in the elucidation of areas of tumor immunology such as cell surface antigens and receptor sites, tumor specific antigens, and immune surveillance of cancer.